I recently came across data around the lack of fiber in the American diet. The daily requirements for fiber range from 25 – 30 grams per day for an adult, but the average American is getting half of that. (source)
While I doubt there is a concerted effort to avoid the nutrient, the standard American diet of highly refined foods simply does not provide enough fiber to support optimal health.
How so? A single apple has 4 grams of fiber but an 8 ounce glass of juice made from 3-4 apples only has 0.5 grams of fiber. Refined white flour has 1/3 the fiber of whole wheat flour. Much of the fiber available in vegetables, fruits, and whole grains is lost during the refining process.
One study found that 58% of food consumed in the U.S. is ‘ultra processed’. With statistics like that, it’s not hard to see how adequate fiber consumption is an issue.
But does it really matter? Yes! Fiber may not be listed as an ‘essential nutrient’ but it is essential to healthy digestion and overall health. Let’s dive into why!
What is Fiber?
Fiber is a type of carbohydrate that comes from the cellular walls of plants. It is often referred to as ‘bulk’ or ‘roughage’ because it is resistant to digestive enzymes, meaning that it does not break down into digestible molecules. Fiber interacts with the body but it passes through the body without being absorbed.
Fiber comes in two forms, soluble and insoluble. Most plant-based foods have both soluble and insoluble fiber but the percentage of each varies by food. It’s often been thought that soluble is the ‘good’ fiber but each type is necessary and plays an equally important role in health.
Soluble fiber is water-soluble (hence the name) and dissolves in the body, producing a gel-like substance that nourishes healthy gut bacteria and slows down digestion. Insoluble fiber expands when exposed to water. It adds bulk to stool and helps push it through the intestines smoothly.
Benefits of a Diet Rich in Fiber
Fiber plays many roles in the body and studies have found that it may even help reduce the chance of diseases like heart disease and diverticulitis. A few of the major roles it plays in optimal health include:
1. Gut Heath
Fiber is the food of choice for the good bacteria living in the gut. There is a lot of talk of probiotics (like kombucha) to increase the numbers of good bacteria in the gut. Increasing the amount of good bacteria is great, but we can support the good bacteria we already have with a fiber rich diet. Prebiotics are a type of fiber that pass through the small intestine undigested and are fermented by gut flora for food in the large intestine.
A lack of fiber to nourish the gut microbiota can lead to die-off of the good bacteria and a shift to other bacteria (and fungi and viruses) ruling the gut. Read more about why gut health is so important for overall health.
2. Regular Bowel Movements
Fiber increases the bulk of stool which helps it pass through the intestines more quickly. It also adds more water to stool which makes it softer and easier to pass. Those who suffer from constipation often find that an increase in dietary fiber helps symptoms.
3. Satiety and Weight Loss
Fiber can help with satiety (the feeling of being full) in a few ways. It takes time to chew fiber rich foods, allowing time to feel the signs of satiety. Plus, chewing is great for digestion! Fiber also adds bulk to food, which makes you feel fuller and slows down digestion, extending the feeling of fullness.
4. Blood Sugar Regulation
Because fiber adds bulk and slows overall digestion, it can help regulate glucose levels by slowing the absorption of glucose into the blood stream.
Fiber Rich Foods
Fiber is most commonly linked to whole grains and legumes. When properly prepared, whole grains and legumes can be a healthy source of dietary fiber. But what about those who follow a paleo diet, or avoid grains and legumes due to allergies or sensitivities?
It is possible, and dare I say not even that difficult, to meet dietary fiber requirements with fruits, vegetables, seeds, and nuts. If you eat multiple servings of fruits and vegetables per day, you are likely at or close to the daily requirements. And if you are eating a varied selection of fruits and vegetables, it’s likely that you are getting a good mix of soluble and insoluble fiber.
Paleo-friendly foods that are particularly high in fiber include avocado, berries, most squash, cruciferous veggies, citrus fruits, and nuts.
Here is a sample menu for a day with 35 grams of fiber, skipping whole grains and legumes.
Breakfast (10g): 3 eggs scrambled with 1 cup sliced mushrooms (1g) and 1 cup spinach (1g) topped with 1/2 serving of easy guacamole (6g); 1/2 cup blueberries (2g) on the side.
Snack (7g): 1 apple (4g) with 1oz almonds (3g).
Lunch (10g): Taco salad with grass-fed ground beef, 3 cups shredded romaine lettuce (3g), 1 bell pepper (2g), 1 cup cherry tomatoes (2g), and 1 oz pumpkin seeds (1g). Top with 1 cup prepared salsa (2g).
Dinner (8g): Chicken roasted with 1 cup Brussels sprouts (3g) and 1/6 serving Curried Carrot and Sweet Potato soup (5g).
If you’re not currently eating adequate amounts of fiber for optimal health, you’ll want to start slow when increasing up to the daily requirements. Allow your body time to adjust by adding five grams per day.